Fix swap issue with nonce update, save a few bytes and improve settings switch feedback

src/shared_context.h

@@ -158,7 +158,7 @@ typedef struct txStringProperties_t {
     char fullAddress[43];
     char fullAmount[50];
     char maxFee[50];
-    char nonce[14];  // size needed to write "NOT Displayed"
+    char nonce[8];  // 10M tx per account ought to be enough for everybody
 } txStringProperties_t;
 
 typedef struct strDataTmp_t {