I am unable to replicate that.

For me check/uncheck -> Close -> Start MM again always start correct version eg. skinned/non skinned.

On Windows 10 Home 64.bit:

1 Install portable mode using defaults and exit.
2 Launch MediaMonkey (non-skinned).exe.
3 In tree, click Music, Drag a track to the player and in Now Playing click on it:

[img]https://i.imgur.com/qNMrT7P.png[/img]

4 In Tools > Options > Skin, and set Font Size to 150% ( https://i.imgur.com/TwBCTL3.png )
5 Click OK.

Expected: Font Size 150% on all text.
Observed: Font Size 150% on some items, but unchanged on tab ("Music"), Search box ("Music"), Tree ("No Playing" etc.), Column Browser headers ("Genre" etc.), Selected window content ("Title:" etc.), and player "MediaMonkey Player"):

[img]https://i.imgur.com/GfQ8HPx.png[/img]

Likewise if instead, at 2 launch is "MediaMonkey .exe" and at 3 "Override skin theme with Windows System Theme (requires restart)" is checkmarked.

Note: This has not yet been filed in Mantis.

On Windows 10 Home 64.bit:

1 Install portable mode using defaults and exit.
2 Launch MediaMonkey.exe.
3 In tree, click Music, Drag a track to the player and in Now Playing click on it:

[img]https://i.imgur.com/qNMrT7P.png[/img]

4 In Tools > Options > Skin, checkmark "Override skin theme with Windows System Theme (requires restart)" and se Font Size to 150% ( https://i.imgur.com/TwBCTL3.png )
5 Click OK.

Expected: Font Size 150% on all text.
Observed: Font Size 150% on some items, but unchanged on tab ("Music"), Search box ("Music"), Tree ("No Playing" etc.), Column Browser headers ("Genre" etc.), Selected window content ("Title:" etc.), and player "MediaMonkey Player"):

[img]https://i.imgur.com/GfQ8HPx.png[/img]

Likewise if instead, launch is "MediaMonkey (non-skinned).exe" and "Override skin theme with Windows System Theme (requires restart)" is left uncheckmarked.

Note: This has not yet been filed in Mantis.

As I replied in other thread. Font size of Preview window is separate from rest of MM Font setting.

MediaMonkey 4 is no longer being developed. If you experience issues like this on MediaMonkey 5 they can be fixed with MediaMonkey 5.

On Windows 10 Home 64-bit.

1 Install in portable mode with default options.
2 Click Tree > Music, drop a track onto player, click track in Now Playing
3 See this:

[img]https://i.imgur.com/2WOH2t2.png[/img]

4 In Tools > Options > Skin, set Font size to 150%
5 Close program, launch MediaMoney.exe, select track.

Expected: "Selected" content font changed to 150%
Observed: "Selected" content font unchanged:

[img]https://i.imgur.com/x6cAMV8.png[/img]

Note: This is not yet filed in Mantis.